DOI:10.2214/AJR.08.2265
AJR 2009; 193:397-409
© American Roentgen Ray Society
Cardiac CT in the Assessment of Acute Chest Pain in the Emergency Department
Gorka Bastarrika1,
Christian Thilo1,2,
Gary F. Headden3,
Peter L. Zwerner2,
Philip Costello1 and
U. Joseph Schoepf1,2
1 Department of Radiology and Radiological Science, Medical University of South
Carolina, Ashley River Tower, MSC 226, 25 Courtenay Dr., Charleston, SC
29425.
2 Division of Cardiology, Department of Medicine, Medical University of South
Carolina, Charleston, SC.
3 Division of Emergency Medicine, Department of Medicine, Medical University of
South Carolina, Charleston, SC.
Received December 17, 2008;
accepted after revision January 22, 2009.
Address correspondence to U. Joseph Schoepf
(schoepf{at}musc.edu).
C. Thilo is a medical consultant for Medrad. P. L. Zwerner is a medical
consultant for Bracco and receives research support from Boehringer-Ingelheim.
P. Costello is a medical consultant for Bracco and receives research support
from Siemens Healthcare. U. J. Schoepf is a medical consultant for Bayer
HealthCare, Bracco, GE Healthcare, Medrad, Siemens Healthcare, and TeraRecon
and receives research support from Bayer HealthCare, Bracco, GE Healthcare,
Medrad, and Siemens Healthcare.
Abstract
OBJECTIVE. The purpose of this article is to describe the current
role of ECG-synchronized CT in the evaluation of patients with acute chest
pain (triple rule-out) in the emergency department. We discuss clinical
contexts of the chest pain algorithm, technical improvements that have enabled
CT to attain its current role for this application, scan protocols and
radiation considerations, the evidence base regarding diagnostic and
prognostic performance, and initial data on the cost-effectiveness of this
promising emerging test.
CONCLUSION. Currently available evidence suggests that CT-based
approaches with modern scan technology are safe, accurate, and potentially
cost-saving, although large-scale clinical trials are needed to ascertain the
precise role of CT in the evaluation of acute chest pain.
Keywords: acute chest pain • acute coronary syndrome • coronary artery disease • CT • triple rule-out
Introduction
Acute chest pain in the emergency department (ED) is one of the most
daunting health care challenges. In 2006, there were 119.2 million visits to
hospital EDs in the United States
[1]. According to the latest
National Hospital Ambulatory Medical Care Survey, the most common specific
reasons given by adult patients (15 years and older) for visiting the ED were,
in descending frequency, chest pain, abdominal pain, back pain, headache, and
shortness of breath, with an estimated 6.4 million patient visits for chest
pain [1]. In the United States
alone the estimated cost of evaluating patients with acute chest pain in the
ED exceeds $10 billion annually
[2]. Although most patients
with acute chest pain do not have a life-threatening underlying condition, a
large proportion of these patients are unnecessarily admitted for observation,
which puts additional strain on already limited resources
[3,
4].
The most clinically relevant conditions causing chest pain that have to be
differentiated in the ED are pulmonary embolism, acute aortic syndrome, and
coronary artery disease presenting as acute coronary syndrome. The last
condition is identified in approximately 15–25% of patients with acute
chest pain who are evaluated in EDs
[5]. Unfortunately, the number
of patients with manifestations of acute myocardial infarction who are
inappropriately discharged from the ED is not negligible
[6–8].
Missed myocardial infarction is the most common reason for litigation stemming
from ED treatment and results in higher awards recovered in malpractice
lawsuits than any other condition
[9–12].
Determining the Most Appropriate Clinical Scenario for CT in the Assessment of Chest Pain in the ED
The classic initial approach to evaluation of acute chest pain consists of
a detailed patient history and physical examination, ECG, and measurement of
cardiac biomarkers. The widely used Thrombosis in Myocardial Infarction (TIMI)
risk score [13] incorporates
this approach and applies one point to each of the following risk factors: age
greater than 65 years, known coronary artery disease (documented previous
coronary artery stenosis > 50%), severe angina (more than two episodes of
chest pain in the preceding 24 hours), ST-segment changes (persistent
depression or transient elevation) on admission ECG, elevated serum markers of
myocardial ischemia (troponins), use of aspirin in the 7 days before
presentation, and three or more conventional risk factors for coronary artery
disease (family history, diabetes mellitus, hypertension,
hypercholesterolemia, smoking). According to this stratification scheme,
patients at high risk (TIMI score, 5–7) usually are referred without
delay for urgent coronary angiography and intervention
[14], whereas patients at
intermediate risk (TIMI score, 3–4) and low risk (TIMI score, 0–2)
are admitted for observation and undergo serial ECG and cardiac biomarker
testing followed by ergometric stress testing.
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Fig. 1A —52-year-old woman with acute atypical chest pain.
Contrast-enhanced retrospectively ECG-gated thoracic CT angiogram shows normal
findings. Study allowed noninvasive rule-out of pulmonary embolism, acute
aortic syndrome, and coronary artery disease with single scan, obviating
further evaluation. Ao = aorta, PA = pulmonary artery, RCA = right coronary
artery, LAD = left anterior descending coronary artery, Cx = circumflex
artery. Volume-rendered images show entire chest (A), pulmonary
vasculature (B), aorta (C), and coronary tree (D).
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Fig. 1B —52-year-old woman with acute atypical chest pain.
Contrast-enhanced retrospectively ECG-gated thoracic CT angiogram shows normal
findings. Study allowed noninvasive rule-out of pulmonary embolism, acute
aortic syndrome, and coronary artery disease with single scan, obviating
further evaluation. Ao = aorta, PA = pulmonary artery, RCA = right coronary
artery, LAD = left anterior descending coronary artery, Cx = circumflex
artery. Volume-rendered images show entire chest (A), pulmonary
vasculature (B), aorta (C), and coronary tree (D).
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Fig. 1C —52-year-old woman with acute atypical chest pain.
Contrast-enhanced retrospectively ECG-gated thoracic CT angiogram shows normal
findings. Study allowed noninvasive rule-out of pulmonary embolism, acute
aortic syndrome, and coronary artery disease with single scan, obviating
further evaluation. Ao = aorta, PA = pulmonary artery, RCA = right coronary
artery, LAD = left anterior descending coronary artery, Cx = circumflex
artery. Volume-rendered images show entire chest (A), pulmonary
vasculature (B), aorta (C), and coronary tree (D).
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Fig. 1D —52-year-old woman with acute atypical chest pain.
Contrast-enhanced retrospectively ECG-gated thoracic CT angiogram shows normal
findings. Study allowed noninvasive rule-out of pulmonary embolism, acute
aortic syndrome, and coronary artery disease with single scan, obviating
further evaluation. Ao = aorta, PA = pulmonary artery, RCA = right coronary
artery, LAD = left anterior descending coronary artery, Cx = circumflex
artery. Volume-rendered images show entire chest (A), pulmonary
vasculature (B), aorta (C), and coronary tree (D).
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Fig. 1E —52-year-old woman with acute atypical chest pain.
Contrast-enhanced retrospectively ECG-gated thoracic CT angiogram shows normal
findings. Study allowed noninvasive rule-out of pulmonary embolism, acute
aortic syndrome, and coronary artery disease with single scan, obviating
further evaluation. Ao = aorta, PA = pulmonary artery, RCA = right coronary
artery, LAD = left anterior descending coronary artery, Cx = circumflex
artery. Curved multiplanar reformatted image shows left anterior descending
coronary artery, right coronary artery, and circumflex artery.
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Excluding the cohort of patients with clear evidence of acute coronary
syndrome who need prompt invasive coronary angiography and intervention and
those with chest pain of definite noncardiac cause, a large number of persons
come to the ED with chest pain of indeterminate origin
[15]. Imaging may have a
significant effect on triage of these patients. Traditional imaging, mainly
conventional chest radiography, may show evidence of a number of causes of
chest pain related to the lung parenchyma, pleura, mediastinum, and thoracic
wall. Most examinations, however, typically yield normal or equivocal results
of limited value. Radionuclide perfusion imaging
[16,
17] and echocardiography
[18,
19] may yield valuable
information, especially in the context of acute coronary syndrome, but cannot
be used to rule out many other disorders, especially those affecting the great
vessels and other noncardiac structures.
The gap may have been successfully filled with improvements in CT scanners,
which can be used for interrogation of the entire thorax in ever shorter scan
times. From a technical perspective, these scanners allow simultaneous
assessment of cardiac structures, the coronary arteries, and diseases of the
great vessels. A single ECG-synchronized scan can be used to evaluate for
pulmonary embolism and acute aortic and coronary syndrome, hence the term
"triple rule-out" for this strategy (Fig.
1A,
1B,
1C,
1D,
1E). Although first
descriptions of this approach
[20] are recent, the power and
utility of this application in the specific scenario of acute chest pain in
the ED were sufficiently intuitive and convincing to result in widespread
adaptation throughout the world. The almost immediate embrace of
ECG-synchronized CT for chest pain evaluation was made possible by the rapid
pace of innovation in CT scanner technology and can be seen as testimony to
the strong desire of the medical community to overcome old, vexing diagnostic
dilemmas in the ED. However, the rapidly advancing integration of
ECG-synchronized CT into the diagnostic algorithm of acute chest pain stands
in contrast to a somewhat limited validation with evidence-based studies of
this approach. Whereas the value of CT in this specific scenario is promising
and intuitive, the use of CT in the evaluation of acute chest pain is yet
another example of how technology with great potential is progressing at a
faster pace than our ability to scientifically evaluate its uses
[21].
Recognizing this quandary, pertinent professional societies rushed to
establish and further develop guidelines for the appropriate use of MDCT that
were based on expert consensus in lieu of a large body of published
literature. For instance, the North American Society of Cardiac Imaging and
the European Society of Cardiac Radiology have released joint statements on
the appropriate use of CT for assessment of acute chest pain
[22]. We emphasize the
potential of ECG-synchronized CT for improving the care of selected patients
with chest pain but also provide a framework for avoiding overuse. In our
clinical practice, we have adopted and expanded on these guidelines for
selecting patients with acute chest pain who are considered eligible to
undergo contrast-enhanced ECG-synchronized CT. We restrict the use of this
test to patients at low to intermediate cardiac risk whose first set of
cardiac biomarker measurements and initial ECG results show no sign of acute
myocardial ischemia and who have an overall TIMI score of 4 or less (Fig.
2A,
2B). We exclude patients with
general contraindications to contrast-enhanced CT, a body mass index (weight
in kilograms divided by height squared in meters) greater than 40, or known
preexisting coronary artery disease (e.g., after coronary artery stent
placement or bypass surgery) with a high pretest likelihood of cardiac causes
of chest pain.
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Fig. 2A —50-year-old man with acute chest pain, family history of
coronary artery disease, intermediate cardiovascular risk, and normal initial
cardiac biomarker and ECG results. Curved multiplanar reformatted (A)
and volume-rendered (B) images from coronary CT angiogram of left
anterior descending coronary artery show calcified plaques causing
nonsignificant stenosis (arrow) in midsegment of artery. Arrowhead
indicates intramyocardial course in distal segment.
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Fig. 2B —50-year-old man with acute chest pain, family history of
coronary artery disease, intermediate cardiovascular risk, and normal initial
cardiac biomarker and ECG results. Curved multiplanar reformatted (A)
and volume-rendered (B) images from coronary CT angiogram of left
anterior descending coronary artery show calcified plaques causing
nonsignificant stenosis (arrow) in midsegment of artery. Arrowhead
indicates intramyocardial course in distal segment.
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Cardiac CT in the ED: Technical Evolution
Electron-beam CT was proposed early on
[23,
24] for the evaluation of
patients arriving in the ED with acute chest pain
[25,
26]. This approach relied on
the total coronary calcium score, called the Agatston score
[27], and was thought to
reflect overall plaque burden
[28]. Technologic development
continued to MDCT, which was used to obtain ECG-synchronized images of the
heart at high spatial and temporal resolution
[29], to quantify coronary
artery calcium [30], and to
detect coronary artery stenosis
[29,
31]. Limitations of
early-generation MDCT scanners were partially overcome with the introduction
of 16-MDCT scanners [32,
33]. More widespread
implementation of this noninvasive technique of cardiac imaging, however, did
not occur until the introduction of 64-MDCT systems
[34].
Sixty-four-MDCT scanners have significantly better spatial and temporal
resolution than previous machines, allowing volumetric acquisition of
isotropic 0.4-mm voxels with up to 0.33-second gantry rotation time and
165-millisecond temporal resolution
[35]. Scan times with these
scanners may be less than 10 seconds when only the heart is evaluated and less
than 20 seconds when the entire thorax is imaged with ECG synchronization
(Fig. 3A,
3B,
3C,
3D). In the 64-MDCT scanner
generation, obtaining motion-free images of the heart and thoracic vasculature
within a reasonable breath-hold time has become feasible and enabled use of
this technique in the ED [20,
36].
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Fig. 3B —40-year-old woman with acute chest pain and dyspnea. Thoracic
CT angiographic findings. Axial reformatted volume-rendered color-mapped image
shows pulmonary hypoperfused areas (arrowheads) mainly at upper
lobes.
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Fig. 3C —40-year-old woman with acute chest pain and dyspnea. Thoracic
CT angiographic findings. Axial CT image at midheart level (C) and
right ventricular end-diastolic volumetric analysis (D) show right
ventricular (RV) enlargement and septal flattening indicating right
ventricular pressure overload. LV = left ventricle.
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Fig. 3D —40-year-old woman with acute chest pain and dyspnea. Thoracic
CT angiographic findings. Axial CT image at midheart level (C) and
right ventricular end-diastolic volumetric analysis (D) show right
ventricular (RV) enlargement and septal flattening indicating right
ventricular pressure overload. LV = left ventricle.
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Limitations concerning arrhythmia, high and variable heart rates, and
extensive calcification, however, have motivated further refinement of CT
technology, resulting in introduction of dual-source CT
[37,
38], which in preliminary
studies [39,
40] has had encouraging
results in the assessment of acute chest pain. We are witnessing the market
entry of scanners with 256 and 320 detector rows
[41–43].
Broader detector arrays may allow complete volume coverage of the heart in a
single heartbeat, reducing susceptibility to arrhythmia
[26,
29,
30]. Until now, this
technology has been investigated strictly for evaluation of the heart. Even if
the technique has potential for use in concomitant assessment of the aorta and
pulmonary vasculature, to our knowledge no data are available on the utility
of this MDCT technology in ED patients. Finally, dual-source CT systems with 2
x 128 detector rows and a temporal resolution of 75 milliseconds have
recently become available and cover the entire chest with ECG synchronization
within less than 1 second and with a drastic reduction in radiation dose.
Determining the Protocol for CT Assessment of Acute Chest Pain
Numerous image acquisition strategies have been proposed for the CT
evaluation of acute chest pain. Those recommendations vary with regard to the
performance of a calcium scoring examination before the contrast-enhanced
acquisition, the most appropriate contrast injection protocol, and general CT
scanner settings
[44–46].
Different approaches include the entire thorax in the scan range or restrict
the coverage to acquisition of a coronary CT angiogram
[47] that excludes the apical
and basal portions of the thorax
[3]. Although the latter
approach ordinarily aids in diagnosis of central pulmonary embolism and aortic
dissection when the images are reconstructed with a large field of view that
includes the full x-y extension of the chest, it may not
depict small peripheral pulmonary emboli in the lung apices and bases, leading
to false-negative results. Extending the z coverage to the entire
length of the thorax can avoid this problem but at the expense of higher
contrast volumes and radiation exposure and increased occurrence of
respiratory motion artifacts in dyspneic patients when older, slower CT
scanners are used.
Particularly with older-generation scanners, for evaluation of patients
with acute chest pain, some centers obtain both a coronary CT angiogram of the
heart only and a non-ECG-synchronized contrast-enhanced CT angiogram of the
thoracic great vessels. The rationale for this approach rests in the desire to
optimize diagnostic quality in all vascular structures. With newer, faster
scanners, however, a routine coronary CT angiographic protocol can be extended
to the entire chest, so that with appropriate contrast injection techniques
[46,
48], there ordinarily is no
difference between the diagnostic quality of an acute chest pain scan and that
of images obtained with protocols dedicated to interrogation of the coronary
arteries, the thoracic aorta, or the pulmonary arteries (Fig.
4A,
4B). Investigators supporting
the inclusion of the entire chest base their rationale on the fact that most
patients admitted to the ED for chest pain have nonspecific symptoms
[20] that can originate
anywhere in the thorax. In our practice we perform coronary CT angiography on
acute chest pain patients who meet the aforementioned eligibility criteria but
have primary clinical evidence of angina (Fig.
5A,
5B). We extend scan coverage
to include the entire chest in patients with less-specific symptoms and a
broad differential diagnosis that includes angina and other relevant causes of
acute chest pain. Our acquisition protocols for these two scenarios are
described in Tables 1,
2,
3 and are based on 64-MDCT and
dual-source CT, which we use in both our acute chest pain center and in our
general ED.
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Fig. 4A —53-year-old woman with acute chest pain radiating to back.
Thoracic CT angiographic findings. Contrast-enhanced axial CT image shows
dissection flap involving descending aorta (arrowhead).
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Fig. 4B —53-year-old woman with acute chest pain radiating to back.
Thoracic CT angiographic findings. Volume-rendered image shows origination of
dissection (arrowhead) distal to left subclavian artery and extension
into abdominal aorta.
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Fig. 5A —43-year-old man with intermediate cardiovascular risk and
acute chest pain. Thoracic CT angiographic findings. Curved multiplanar
reformatted (A) and volume-rendered (B) images of left anterior
descending coronary artery show intense vascular remodeling of entire vessel
with significant stenosis caused by predominantly noncalcified plaque
(arrow) involving mid and distal segments.
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Fig. 5B —43-year-old man with intermediate cardiovascular risk and
acute chest pain. Thoracic CT angiographic findings. Curved multiplanar
reformatted (A) and volume-rendered (B) images of left anterior
descending coronary artery show intense vascular remodeling of entire vessel
with significant stenosis caused by predominantly noncalcified plaque
(arrow) involving mid and distal segments.
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Different approaches also exist regarding the exact time point at which to
perform this examination after a patient arrives in the ED with acute chest
pain. The point in the diagnostic algorithm at which to perform CT depends on
the risk profile and general condition of the patient and on the local
availability of the equipment. At centers that do not provide circadian CT
services, including ECG-synchronized CT for acute chest pain, CT likely is
used as it is for traditional evaluations, that is, patients undergo specific
testing, such as ergometric stress testing and nuclear myocardial perfusion
imaging, the morning after ED admission. At centers such as ours that do
perform CT and interpret images during off hours, cardiac CT is ordinarily
used for front-line triage of suitable patients. It is performed immediately
after the general assessment and after initial ECG and the first set of
cardiac enzyme measurements suggest the absence of acute myocardial ischemia.
Use of the latter approach can maximize time- and cost-effectiveness because
most clinically relevant causes of chest pain can be ruled out and patient
care steered toward discharge or hospital admission. After 4 years of
performing acute chest pain CT at our institution, we feel comfortable enough
in our approach to discharge a patient on the basis of normal findings, if the
overall clinical scenario is supportive of such a decision. We occasionally
also perform coronary CT angiography on acute chest pain patients already
admitted to the hospital, to assist in patient care in accordance with general
guidelines for appropriate use of coronary CT angiography in the evaluation of
atypical chest pain [49].
Radiation Dose
Radiation dose at CT in general and cardiac CT in particular has become a
focus of public attention. With current equipment, the estimated effective
dose for retrospectively ECG-gated coronary CT angiography can be
approximately 20 mSv [50] and
higher, especially when the scan coverage includes the entire chest. For
instance, with a standard 2 x 64 detector-row dual-source CT protocol
for chest pain evaluation (120 kV, 320 mAs/rotation), the radiation dose is
estimated at 14.7–16.7 mSv
[51]. This radiation dose is
likely well invested if life-threatening pathologic conditions can be
noninvasively diagnosed or if further testing can be obviated on the basis of
a normal result.
Although the radiation dose at cardiac CT as a novel test is receiving
considerable scrutiny, it is often forgotten that the current standard-of-care
evaluation of acute chest pain can involve considerable radiation exposure
from procedures such as rest–stress 99mTc-sestamibi
scintigraphy (
20 mSv), 201Tl scan ( 40 mSv), and
conventional diagnostic invasive coronary catheterization (5–10 mSv)
[52,
53], the last involving
substantial additional risk of complications. However, the power, ease of
performance, and increasing availability of CT for acute chest pain have the
looming potential for overuse, with CT pulmonary angiography being the
foremost warning precedent. The best defense for containing overuse is
appropriate patient selection. Although guidelines for suitable indications
are still emerging, individual assessment (i.e., for each patient) of the
pretest likelihood of specific cardiovascular disease and of the
risk-to-benefit ratio that governs the use of all medical procedures that
involve potential risk (e.g., radiation) remains imperative.
On the technical side, all available means should be used to lower
radiation dose. One of these steps is simply lowering the tube voltage for
imaging of slim persons, which can reduce radiation exposure as much as 88%
[54,
55]. A more advanced technique
is ECG-dependent tube current modulation
[56], by which radiation dose
is automatically lowered during cardiac phases that are undesirable for
morphologic image reconstruction (typically systole). Use of this technique
can reduce radiation dose as much as 44%
[57]. With these approaches,
radiation for a dual-source CT coronary angiogram, for instance, may result in
an estimated mean effective dose of 7.8–8.8 mSv
[58].
The most significant radiation dose savings have been reported with the
recently re-introduced prospective ECG-triggering approach
[58–60].
Use of this acquisition technique ordinarily results in diagnostic image
quality for almost all coronary segments
[61], maintenance of accuracy
for detection of coronary artery stenosis, and drastically reduced radiation
dose (1.2–4.4 mSv) [62].
This technique, however, has been recognized to be highly sensitive to high
and irregular heart rates. Thus its use should be restricted to patients with
stable and slow (< 65–70 beats/min) heart rates. Technical
developments such as broadening the portion of the RR-interval during which
radiation is applied (ECG padding) and adaptive online monitoring of the ECG
for the occurrence of extra systoles
[63] are expected to increase
the number of patients who can successfully undergo imaging with this
technique. The potential of using prospectively ECG-triggered CT acquisition
techniques in the assessment of chest pain in ED patients is being
explored.
Evidence Base: Coronary Artery Calcium Quantification in the ED
Coronary artery calcification is considered a quantifiable marker
[27] of atherosclerotic plaque
[64], although there is no
clear relation between the calcified plaque burden and the severity of
coronary artery stenosis [65].
CT coronary artery calcium scoring consequently has been proposed as a tool
for stratifying cardiac risk
[66,
67]. Various studies of the
general population have been conducted to evaluate the prognostic value of
coronary calcium quantification in predicting future coronary events in both
persons with and those without symptoms
[68–76].
In the specific clinical scenario of acute chest pain in the ED, three
initial studies performed with electron-beam CT have been conducted to assess
the usefulness of coronary calcium scoring; however, the number of patients in
the studies was relatively limited. McLaughlin et al.
[25] evaluated 134 patients
with acute chest pain and normal or nondiagnostic ECGs. On the basis of the
98% negative predictive value found in the study, the authors concluded that
patients without coronary artery calcification (Agatston score, 0) can be
safely discharged. Laudon et al.
[26] came to similar
conclusions in a prospective observational study that included 105 patients
with acute chest pain who underwent calcium scoring and other cardiac testing
considered necessary by referring physicians (treadmill exercise testing,
conventional coronary angiography, radionuclide stress testing, and
echocardiography). Those authors suggested that no further testing is needed
for patients with normal initial cardiac enzyme levels, normal or
indeterminate ECG findings, and a calcium score of 0. Georgiou et al.
[69], in a prospective
follow-up study that included 192 patients with acute chest pain, found a
higher annual event rate among subjects with high coronary artery calcium
scores than subjects with no coronary artery calcification. Accordingly, those
authors concluded that the absence of coronary artery calcification portends
very low risk of future cardiac events (annual event rate < 1%) in this
population.
In the era of MDCT we continue to perform coronary artery calcium scoring
as a component of every contrast-enhanced cardiac CT examination for suspected
coronary artery disease, including acute chest pain CT. We find this test
useful for familiarizing the patient with the scan procedure (e.g.,
breath-hold commands), and, in the case of dedicated coronary CT angiography,
for determining the exact scan coverage. More important, with this approach we
aim at aiding appropriate cardiac risk management (i.e., with lipid-lowering
therapy) in patients with acute chest pain who have cardiac risk factors and
coronary artery calcification but otherwise no identifiable acute disease.
Although the presence of heavy calcification continues to be a relative
limitation to accurate coronary artery stenosis grading
[77], we do not exclude
patients from contrast-enhanced cardiac CT on the basis of a high calcium
score. We believe that improvements in the temporal and spatial resolution of
CT acquisition and the development of more advanced visualization techniques
have significantly enhanced our ability to evaluate heavily calcified vessel
segments [78].
Evidence Base: Contrast-Enhanced CT Angiography in the ED
The numerous noncardiac causes of acute chest pain that have morphologic
correlates in thoracic vascular structures, mediastinum, lung, and chest wall
can be easily visualized with CT
[79]. The role of CT in the
assessment of acute disease involving the great vessels of the thorax is well
established, and this technique is currently considered the method of choice
for evaluating pulmonary embolism (Fig.
6A,
6B)
[80–82]
and acute aortic syndromes (Figs.
7A,
7B and
8A,
8B)
[83,
84]. In addition, substantial
technical improvement in scanners has facilitated accurate evaluation of
coronary artery disease with cardiac CT protocols. In selected patient
populations, 64-MDCT coronary angiography can depict significant coronary
artery stenosis with sensitivity ranging from 86% to 100% and specificity from
92% to 98%
[85–93]
compared with invasive coronary angiography. With dual-source CT technology
and improved temporal resolution, these high performance indexes have been
found to translate to patient populations with higher average heart rates
without the use of rate-controlling pharmacologic intervention
[94–98].
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Fig. 6A —61-year-old man with chest pain. Thoracic CT angiographic
findings. Multiplanar reformatted coronal image shows left central pulmonary
artery embolism (arrowhead) extending to segmental lingula and left
inferior lower lobe branches.
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Fig. 6B —61-year-old man with chest pain. Thoracic CT angiographic
findings. Reformatted coronal volume-rendered color-mapped image shows
corresponding perfusion defects. Arrowhead indicates embolism.
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Fig. 8A —58-year-old man admitted in emergency department because of
acute chest pain radiating to back. Diagnosis is complex aortic dissection.
Contrast-enhanced axial CT image shows involvement of ascending and descending
aorta (arrows).
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Fig. 8B —58-year-old man admitted in emergency department because of
acute chest pain radiating to back. Diagnosis is complex aortic dissection.
Contrast-enhanced axial CT image shows flap with whirl-like complex structure
at aortic arch.
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One of the first studies of the efficacy of CT in the diagnosis of acute
coronary syndrome in the ED was conducted by Sato et al.
[99] with 4- and 16-MDCT
systems. Morphologically defining acute coronary syndrome as coronary artery
stenosis 
75% accompanied by low-attenuation plaque and myocardial
perfusion defects, the authors found sensitivity and specificity of 95.5% and
88.9% in identification of this entity with CT. Subsequent studies have been
conducted to evaluate the performance of coronary 16- and 64-MDCT angiography
in the assessment of signs and symptoms of acute coronary syndrome in the ED
[100–104].
In a preliminary study, Hoffmann et al.
[104] evalu ated 40 patients
with chest pain who were awaiting hospital admission for ruling out of acute
coronary syndrome without diagnostic ECG changes suggestive of ischemia and
with normal initial cardiac enzyme levels. This cohort of patients underwent
contrast-enhanced MDCT coronary angiography before hospital admission in
addition to the standard-of-care diagnostic evaluation. The authors concluded
that CT-based detection of significant coronary artery stenosis can decrease
the number of unnecessary hospital admissions with out reducing rates of
appropriate admission. The same group
[100] also conducted a blind
prospective study with 103 ED patients and found that the absence of
significant coronary artery stenosis and significant coronary atherosclerotic
plaque was an accurate predictor of the absence of acute coronary syndrome
during hospitalization and a 5-month follow-up period.
In another study, Gallagher et al.
[101] compared the accuracy
of coronary MDCT angiography with that of stress nuclear imaging in the
diagnosis of acute coronary syndrome and in prediction of major adverse
cardiac events during 30 days of follow-up of 85 patients at low risk with
chest pain. The authors found that the accuracy of MDCT is at least as good as
that of stress nuclear imaging in the diagnosis and exclusion of acute
coronary syndrome in this patient population. In a randomized controlled trial
in which the subjects were patients at low risk with acute chest pain,
Goldstein et al. [102]
compared the performance of CT with the standard of care, including serial
ECGs, measurement of cardiac biomarkers, and same-day stress myocardial
perfusion imaging. They found that in this patient population, the accuracy
and safety of MDCT are similar to those of the standard of care in the
diagnosis of acute coronary syndrome, time to diagnosis is shortened, and
costs are potentially reduced with MDCT. Goldstein et al. also addressed the
limitations of CT by pointing to the added value of myocardial perfusion
imaging for determining the physiologic significance of intermediate-severity
coronary lesions and unevaluable coronary artery segments.
Rubinshtein et al. [103]
examined the usefulness of CT for initial triage of 58 patients with possible
acute coronary syndrome and for assessment of clinical outcome over a 15-month
follow-up period. No patient discharged on the basis of normal CT findings
died or had myocardial infarction during this period. From this observation
the authors concluded that MDCT has high accuracy in the diagnosis of acute
coronary syndrome and that normal CT findings are predictive of a low rate of
major adverse cardiovascular events and of favorable outcome during follow-up.
In a separate publication, Rubinshtein et al.
[105] reported the influence
of CT findings on clinical decision making and argued that this diagnostic
technique decreased the need for hospitalization almost one half in their
patient cohort.
The broader use of CT as a comprehensive tool for assessing acute chest
pain and differentiating cardiac and noncardiac causes in patients in stable
condition in the ED (triple rule-out) was initially evaluated with 16-MDCT
[20]. Unlike protocols that
entail coronary CT angiography, the major advantage of this approach is its
potential in the exclusion and diagnosis of major life-threatening thoracic
diseases, including acute coronary syndrome, pulmonary embolism, and acute
aortic syndrome [106], and of
noncardiovascular causes of acute chest pain
[20].
It is a clinical reality that a large number of patients with acute chest
pain have noncardiac conditions underlying the symptoms. Several publications
describe the usefulness of comprehensive ECG-synchronized CT evaluation of the
entire chest for patients with acute chest pain. In our first published
[48] series of patients, we
used ECG-gated 64-MDCT of the entire thorax to evaluate 23 patients with
equivocal acute chest pain. Compared with the findings for a matched control
sample who underwent catheter angiography for emergency cardiac evaluation,
the total length of hospitalization, charges for ED care at discharge, and
total hospital charges were significantly lower among the subjects undergoing
CT. We found that use of ECG-gated 64-MDCT enables rapid triage of patients to
establish the underlying cardiac and noncardiac causes of chest pain and that
use of ECG-gated CT angiography of the entire thorax may help to reduce costs
and the length of hospitalization.
On the basis of dual-source CT findings, Schertler et al.
[40] found that use of a
comprehensive protocol that includes the entire chest results in
diagnostic-quality images of the thoracic aorta and pulmonary and coronary
arteries in patients with acute chest pain. Johnson et al.
[39] analyzed the diagnostic
accuracy of a dual-source CT protocol for chest pain assessment in 109
patients. The most common diagnoses in their patient sample, in decreasing
frequency, were coronary artery disease, valvular and myocardial disease,
pulmonary embolism, and acute aortic syndrome. These findings are in
accordance with those in other series and with clinical experience, in which
acute aortic syndromes constitute the least frequent underlying cause of acute
chest pain. The authors found that compared with invasive coronary
angiography, dual-source CT had an overall sensitivity of 98% and a
sensitivity and negative predictive value of 100% in identification of the
causative pathologic mechanism and the diagnosis of coronary artery
stenosis.
Cost-Effectiveness
The cost of ED evaluation and treatment of patients with chest pain is one
of the greatest burdens on health care systems. Among the almost 6 million
patients who annually go to an ED because of acute chest pain, only
approximately 20% receive the diagnosis of coronary heart disease
[107], and a large number of
these patients are unnecessarily admitted for observation or hospitalization
[2]. In 2005, there were a
total of 1,340,482 discharges for nonspecific chest pain. According to
national statistics on community hospital stays in the United States
[2], in 2006 the number of
discharges for nonspecific chest pain was 856,948, with a mean length of stay
of 1.8 days. That year the national bill for nonspecific chest pain amounted
to more than $11.2 billion.
The current risk stratification of patients with acute chest pain but
nondiagnostic ECG results and normal initial cardiac enzyme levels is
insufficient. To our knowledge, results of all analyses available to date
agree that compared with the traditional standard of care, integration of CT
into the diagnostic algorithm for acute chest pain has potential for reducing
time to diagnosis, decreasing the number of unnecessary hospital admissions,
and lowering cost [48,
100,
102]. Cost savings ranging
from hundreds to thousands of dollars per patient have been reported
[48,
102]. Ladapo et al.
[108] developed a simulation
model to compare the costs and health effects of coronary CT angiography for
acute chest pain with a standard-of-care algorithm that included measurement
of cardiac markers for triage of patients to early discharge, stress testing,
or invasive coronary angiography. According to the simulations, among men the
incremental cost-effectiveness ratio for coronary CT angiography was $6,400
per quality-adjusted life year; among women, coronary CT angiography was
cost-saving. The authors concluded that coronary CT angiography–based
triage of patients with low-risk chest pain is moderately more cost-effective
than the standard of care, particularly for women, who traditionally present a
greater diagnostic challenge in the evaluation of acute chest pain than do
men.
The cost-effectiveness of use of CT for evaluation of acute chest pain
depends, among many other factors, on the level of reimbursement for the
procedure. A 2007 study [109]
showed that reimbursement for CT in the evaluation of chest pain was at levels
comparable with those for pulmonary CT angiography and CT angiography of the
thoracic aorta. This type of reimbursement must be weighed against the
complexity of the examination, which typically requires advanced scanner
technology, expertise, and postprocessing efforts and a larger number of
professionals than do more traditional routine CT angiographic procedures.
Consequently, the decision to use ECG-synchronized CT in the evaluation of
patients with acute chest pain in the ED must entail many factors, not only
the availability of the latest-generation CT scanners.
Conclusion
The current standard-of-care approach to ED evaluation of patients with
acute chest pain has substantial deficiencies. The persistence of missed
diagnoses of acute myocardial infarction and unnecessary admissions to the
hospital suggests the need for new algorithms. The widespread availability of
ever more advanced CT technology has led to the rapid integration of
ECG-synchronized CT into the diagnostic algorithm for acute chest pain.
Currently available evidence suggests that CT-based approaches with modern
scan technology are safe, accurate, and potentially cost-saving. Large-scale
clinical trials are needed to further evaluate the precise role of CT in the
evaluation of acute chest pain.
References
- Pitts SR, Niska RW, Xu J, Burt CW. National Hospital Ambulatory
Medical Care Survey: 2006 emergency department summary. National health
statistics reports; no 7. Hyattsville, MD: National Center for Health
Statistics, 2008;
www.cdc.gov/nchs.
Accessed May 10, 2009
- Healthcare Cost and Utilization Project Web site. Rockville, MD:
Agency for Healthcare Research and Quality, 2006;
http://www.hcup.ahrq.gov.
Accessed May 10, 2009
- Hoffmann U, Pena AJ, Cury RC, et al. Cardiac CT in emergency
department patients with acute chest pain.
RadioGraphics 2006;26
: 963–978[Abstract/Free Full Text]
- Fineberg HV, Scadden D, Goldman L. Care of patients with a low
probability of acute myocardial infarction: cost effectiveness of alternatives
to coronary-care-unit admission. N Engl J Med1984; 310:1301
–1307[Abstract]
- Pozen MW, D'Agostino RB, Selker HP, Sytkowski PA, Hood WB Jr. A
predictive instrument to improve coronary-care-unit admission practices in
acute ischemic heart disease: a prospective multicenter clinical trial.
N Engl J Med 1984;310
:1273
–1278[Abstract]
- Schull MJ, Vermeulen MJ, Stukel TA. The risk of missed diagnosis of
acute myocardial infarction associated with emergency department volume.
Ann Emerg Med 2006;48
: 647–655[CrossRef][Medline]
- Chan WK, Leung KF, Lee YF, Hung CS, Kung NS, Lau FL. Undiagnosed
acute myocardial infarction in the accident and emergency department: reasons
and implications. Eur J Emerg Med 1998;5
: 219–224[Medline]
- McCarthy BD, Beshansky JR, D'Agostino RB, Selker HP. Missed
diagnoses of acute myocardial infarction in the emergency department: results
from a multicenter study. Ann Emerg Med1993; 22:579
–582[CrossRef][Medline]
- Collinson PO, Premachandram S, Hashemi K. Prospective audit of
incidence of prognostically important myocardial damage in patients discharged
from emergency department. BMJ 2000;320
:1702
–1705[Abstract/Free Full Text]
- White AA, Wright SW, Blanco R, et al. Cause-and-effect analysis of
risk management files to assess patient care in the emergency department.
Acad Emerg Med 2004;11
:1035
–1041[CrossRef][Medline]
- Freas GC. Medicolegal aspects of acute myocardial infarction.
Emerg Med Clin North Am 2001;19
: 511–521[CrossRef][Medline]
- Rusnak RA, Stair TO, Hansen K, Fastow JS. Litigation against the
emergency physician: common features in cases of missed myocardial infarction.
Ann Emerg Med 1989;18
:1029
–1034[CrossRef][Medline]
- Antman EM, Cohen M, Bernink PJ, et al. The TIMI risk score for
unstable angina/non-ST elevation MI: a method for prognostication and
therapeutic decision making. JAMA 2000;284
: 835–842[Abstract/Free Full Text]
- Braunwald E, Antman EM, Beasley JW, et al. ACC/AHA guideline update
for the management of patients with unstable angina and non-ST-segment
elevation myocardial infarction–2002: summary article: a report of the
American College of Cardiology/American Heart Association Task Force on
Practice Guidelines (Committee on the Management of Patients With Unstable
Angina). Circulation 2002;106
:1893
–1900[Free Full Text]
- Meyer MC, Mooney RP, Sekera AK. A critical pathway for patients
with acute chest pain and low risk for short-term adverse cardiac events: role
of outpatient stress testing. Ann Emerg Med2006; 47:435[CrossRef][Medline]
- Radensky PW, Hilton TC, Fulmer H, McLaughlin BA, Stowers SA.
Potential cost effectiveness of initial myocardial perfusion imaging for
assessment of emergency department patients with chest pain. Am J
Cardiol 1997; 79:595
–599[CrossRef][Medline]
- Udelson JE, Beshansky JR, Ballin DS, et al. Myocardial perfusion
imaging for evaluation and triage of patients with suspected acute cardiac
ischemia: a randomized controlled trial. JAMA2002; 288:2693
–2700[Abstract/Free Full Text]
- Nanuwa K, Chambers J, Senior R. Echocardiography for chest pain in
the emergency department. Int J Clin Pract2005; 59:1374
–1376[CrossRef][Medline]
- Lewis WR. Echocardiography in the evaluation of patients in chest
pain units. Cardiol Clin 2005;23
: 531–539[CrossRef][Medline]
- White CS, Kuo D, Kelemen M, et al. Chest pain evaluation in the
emergency department: can MDCT provide a comprehensive evaluation?
AJR 2005; 185:533
–540[Abstract/Free Full Text]
- Schoepf UJ. Computed tomography for pulmonary embolism diagnosis:
the making of a reference standard. J Thromb Haemost2005; 3:1924
–1925[CrossRef][Medline]
- Stillman AE, Oudkerk M, Ackerman M, et al. Use of multidetector
computed tomography for the assessment of acute chest pain: a consensus
statement of the North American Society of Cardiac Imaging and the European
Society of Cardiac Radiology. Int J Cardiovasc Imaging2007; 23:415
–427[CrossRef][Medline]
- Wood EH. Noninvasive three-dimensional viewing of the motion and
anatomical structure of the heart, lungs, and circulatory system by high speed
computerized X-ray tomography. CRC Crit Rev Biochem1979; 7:161
–186[Medline]
- Ritman EL, Kinsey JH, Robb RA, Gilbert BK, Harris LD, Wood EH.
Three-dimensional imaging of heart, lungs, and circulation.
Science 1980; 210:273
–280[Abstract/Free Full Text]
- McLaughlin VV, Balogh T, Rich S. Utility of electron beam computed
tomography to stratify patients presenting to the emergency room with chest
pain. Am J Cardiol 1999;84
: 327–328[CrossRef][Medline]
- Laudon DA, Vukov LF, Breen JF, Rumberger JA, Wollan PC, Sheedy PF
2nd. Use of electron-beam computed tomography in the evaluation of chest pain
patients in the emergency department. Ann Emerg Med1999; 33:15
–21[CrossRef][Medline]
- Agatston AS, Janowitz WR, Hildner FJ, Zusmer NR, Viamonte M Jr,
Detrano R. Quantification of coronary artery calcium using ultrafast computed
tomography. J Am Coll Cardiol 1990;15
: 827–832[Abstract]
- Budoff MJ, Achenbach S, Blumenthal RS, et al. Assessment of
coronary artery disease by cardiac computed tomography: a scientific statement
from the American Heart Association Committee on Cardiovascular Imaging and
Intervention, Council on Cardiovascular Radiology and Intervention, and
Committee on Cardiac Imaging, Council on Clinical Cardiology.
Circulation 2006;114
:1761
–1791[Free Full Text]
- Ohnesorge B, Flohr T, Becker C, et al. Cardiac imaging by means of
electrocardiographically gated multisection spiral CT: initial experience.
Radiology 2000;217
: 564–571[Abstract/Free Full Text]
- Kopp AF, Ohnesorge B, Becker C, et al. Reproducibility and accuracy
of coronary calcium measurements with multi-detector row versus electron-beam
CT. Radiology 2002;225
: 113–119[Abstract/Free Full Text]
- Achenbach S, Ulzheimer S, Baum U, et al. Non-invasive coronary
angiography by retrospectively ECG-gated multislice spiral CT.
Circulation 2000;102
:2823
–2828[Abstract/Free Full Text]
- Kuettner A, Beck T, Drosch T, et al. Diagnostic accuracy of
noninvasive coronary imaging using 16-detector slice spiral computed
tomography with 188 ms temporal resolution. J Am Coll
Cardiol 2005; 45:123
–127[Abstract/Free Full Text]
- Ropers D, Baum U, Pohle K, et al. Detection of coronary artery
stenoses with thin-slice multidetector row spiral computed tomography and
multiplanar reconstruction. Circulation2003; 107:664
–666[Abstract/Free Full Text]
- Hamon M, Morello R, Riddell JW. Coronary arteries: diagnostic
performance of 16-versus 64-section spiral CT compared with invasive coronary
angiography: meta-analysis. Radiology2007; 245:720
–731[Abstract/Free Full Text]
- Flohr T, Stierstorfer K, Raupach R, Ulzheimer S, Bruder H.
Performance evaluation of a 64-slice CT system with z-flying focal spot.
Rofo 2004; 176:1803
–1810[Medline]
- White CS, Kuo D. Chest pain in the emergency department: role of
multidetector CT. Radiology 2007;245
: 672–681[Abstract/Free Full Text]
- Flohr TG, McCollough CH, Bruder H, et al. First performance
evaluation of a dual-source CT (DSCT) system. Eur
Radiol 2006; 16:256
–268[CrossRef][Medline]
- Johnson TR, Nikolaou K, Wintersperger BJ, et al. Dual-source CT
cardiac imaging: initial experience. Eur Radiol2006; 16:1409
–1415[CrossRef][Medline]
- Johnson TR, Nikolaou K, Becker A, et al. Dual-source CT for chest
pain assessment. Eur Radiol 2008;18
: 773–780[CrossRef][Medline]
- Schertler T, Scheffel H, Frauenfelder T, et al. Dual-source
computed tomography in patients with acute chest pain: feasibility and image
quality. Eur Radiol 2007;17
:3179
–3188[CrossRef][Medline]
- Kido T, Kurata A, Higashino H, et al. Cardiac imaging using
256-detector row four-dimensional CT: preliminary clinical report.
Radiat Med 2007;25
: 38–44[CrossRef][Medline]
- Mori S, Kondo C, Suzuki N, Hattori A, Kusakabe M, Endo M.
Volumetric coronary angiography using the 256-detector row computed tomography
scanner: comparison in vivo and in vitro with porcine models. Acta
Radiol 2006; 47:186
–191[CrossRef][Medline]
- Rybicki FJ, Otero HJ, Steigner ML, et al. Initial evaluation of
coronary images from 320-detector row computed tomography. Int J
Cardiovasc Imaging 2008; 24:535
–546[CrossRef][Medline]
- Johnson TR, Nikolaou K, Wintersperger BJ, et al. ECG-gated 64-MDCT
angiography in the differential diagnosis of acute chest pain.
AJR 2007; 188:76
–82[Abstract/Free Full Text]
- Litmanovich D, Zamboni GA, Hauser TH, Lin PJ, Clouse ME,
Raptopoulos V. ECG-gated chest CT angiography with 64-MDCT and tri-phasic IV
contrast administration regimen in patients with acute non-specific chest
pain. Eur Radiol 2008;18
: 308–317[CrossRef][Medline]
- Vrachliotis TG, Bis KG, Haidary A, et al. Atypical chest pain:
coronary, aortic, and pulmonary vasculature enhancement at biphasic
single-injection 64-section CT angiography. Radiology2007; 243:368
–376[Abstract/Free Full Text]
- Lee HY, Yoo SM, White CS. Coronary CT angiography in emergency
department patients with acute chest pain: triple rule-out protocol versus
dedicated coronary CT angiography. Int J Cardiovasc
Imaging 2009; 25:319
–326[CrossRef][Medline]
- Savino G, Herzog C, Costello P, Schoepf UJ. 64 slice cardiovascular
CT in the emergency department: concepts and first experiences.
Radiol Med 2006;111
: 481–496[CrossRef][Medline]
- Hendel RC, Patel MR, Kramer CM, et al.
ACCF/ACR/SCCT/SCMR/ASNC/NASCI/SCAI/SIR 2006 appropriateness criteria for
cardiac computed tomography and cardiac magnetic resonance imaging: a report
of the American College of Cardiology Foundation Quality Strategic Directions
Committee Appropriateness Criteria Working Group, American College of
Radiology, Society of Cardiovascular Computed Tomography, Society for
Cardiovascular Magnetic Resonance, American Society of Nuclear Cardiology,
North American Society for Cardiac Imaging, Society for Cardiovascular
Angiography and Interventions, and Society of Interventional Radiology.
J Am Coll Cardiol 2006;48
:1475
–1497[Free Full Text]
- Hirai N, Horiguchi J, Fujioka C, et al. Prospective versus
retrospective ECG-gated 64-detector coronary CT angiography: assessment of
image quality, stenosis, and radiation dose. Radiology2008; 248:424
–430[Abstract/Free Full Text]
- Ketelsen D, Luetkhoff MH, Thomas C, et al. Estimation of the
radiation exposure of a chest pain protocol with ECG-gating in dual-source
computed tomography. Eur Radiol 2009;19
: 37–41[CrossRef][Medline]
- United Nations Scientific Committee on the Effects of Atomic
Radiation. Sources and effects of ionizing radiation. New York,
NY: UNSCEAR, 2000: 654
- Mettler FA Jr, Huda W, Yoshizumi TT, Mahesh M. Effective doses in
radiology and diagnostic nuclear medicine: a catalog.
Radiology 2008;248
: 254–263[Abstract/Free Full Text]
- Leschka S, Stolzmann P, Schmid FT, et al. Low kilovoltage cardiac
dual-source CT: attenuation, noise, and radiation dose. Eur
Radiol 2008; 18:1809
–1817[CrossRef][Medline]
- Abada HT, Larchez C, Daoud B, Sigal-Cinqualbre A, Paul JF. MDCT of
the coronary arteries: feasibility of low-dose CT with ECG-pulsed tube current
modulation to reduce radiation dose. AJR2006; 186:S387
–S390[Abstract/Free Full Text]
- Jakobs TF, Becker CR, Ohnesorge B, et al. Multislice helical CT of
the heart with retrospective ECG gating: reduction of radiation exposure by
ECG-controlled tube current modulation. Eur Radiol2002; 12:1081
–1086[CrossRef][Medline]
- Poll LW, Cohnen M, Brachten S, Ewen K, Modder U. Dose reduction in
multi-slice CT of the heart by use of ECG-controlled tube current modulation
("ECG pulsing"): phantom measurements.
Rofo 2002; 174:1500
–1505[Medline]
- Stolzmann P, Scheffel H, Schertler T, et al. Radiation dose
estimates in dual-source computed tomography coronary angiography.
Eur Radiol 2008;18
: 592–599[CrossRef][Medline]
- Scheffel H, Alkadhi H, Leschka S, et al. Lowdose CT coronary
angiography in the step-and-shoot mode: diagnostic performance.
Heart 2008; 94:1132
–1137[Abstract/Free Full Text]
- Husmann L, Valenta I, Gaemperli O, et al. Feasibility of low-dose
coronary CT angiography: first experience with prospective ECG-gating.
Eur Heart J 2008;29
: 191–197[Abstract/Free Full Text]
- Stolzmann P, Leschka S, Scheffel H, et al. Dual-source CT in
step-and-shoot mode: noninvasive coronary angiography with low radiation dose.
Radiology 2008;249
: 71–80[Abstract/Free Full Text]
- Scheffel H, Alkadhi H, Leschka S, et al. Low-dose CT coronary
angiography in the step-and-shoot mode: diagnostic performance.
Heart 2008; 94:1132
–1137[Abstract/Free Full Text]
- Earls JP, Berman EL, Urban BA, et al. Prospectively gated
transverse coronary CT angiography versus retrospectively gated helical
technique: improved image quality and reduced radiation dose.
Radiology 2008;246
: 742–753[Abstract/Free Full Text]
- Rifkin RD, Parisi AF, Folland E. Coronary calcification in the
diagnosis of coronary artery disease. Am J Cardiol1979; 44:141
–147[CrossRef][Medline]
- O'Rourke RA, Brundage BH, Froelicher VF, et al. American College of
Cardiology/American Heart Association Expert Consensus document on
electron-beam computed tomography for the diagnosis and prognosis of coronary
artery disease. Circulation 2000;102
: 126–140[Free Full Text]
- Rumberger JA, Brundage BH, Rader DJ, Kondos G. Electron beam
computed tomographic coronary calcium scanning: a review and guidelines for
use in asymptomatic persons. Mayo Clin Proc1999; 74:243
–252[Abstract]
- Budoff MJ, Georgiou D, Brody A, et al. Ultrafast computed
tomography as a diagnostic modality in the detection of coronary artery
disease: a multicenter study. Circulation1996; 93:898
–904[Abstract/Free Full Text]
- Detrano R, Hsiai T, Wang S, et al. Prognostic value of coronary
calcification and angiographic stenoses in patients undergoing coronary
angiography. J Am Coll Cardiol 1996;27
: 285–290[Abstract]
- Georgiou D, Budoff MJ, Kaufer E, Kennedy JM, Lu B, Brundage BH.
Screening patients with chest pain in the emergency department using electron
beam tomography: a follow-up study. J Am Coll Cardiol2001; 38:105
–110[Abstract/Free Full Text]
- Kennedy J, Shavelle R, Wang S, Budoff M, Detrano RC. Coronary
calcium and standard risk factors in symptomatic patients referred for
coronary angiography. Am Heart J 1998;135
: 696–702[CrossRef][Medline]
- Arad Y, Goodman KJ, Roth M, Newstein D, Guerci AD. Coronary
calcification, coronary disease risk factors, C-reactive protein, and
atherosclerotic cardiovascular disease events: the St. Francis Heart Study.
J Am Coll Cardiol 2005;46
: 158–165[Abstract/Free Full Text]
- Arad Y, Spadaro LA, Goodman K, Newstein D, Guerci AD. Prediction of
coronary events with electron beam computed tomography. J Am Coll
Cardiol 2000; 36:1253
–1260[Abstract/Free Full Text]
- Kondos GT, Hoff JA, Sevrukov A, et al. Electron-beam tomography
coronary artery calcium and cardiac events: a 37-month follow-up of 5635
initially asymptomatic low- to intermediate-risk adults.
Circulation 2003;107
:2571
–2576[Abstract/Free Full Text]
- Raggi P, Callister TQ, Cooil B, et al. Identification of patients
at increased risk of first unheralded acute myocardial infarction by
electron-beam computed tomography. Circulation2000; 101:850
–855[Abstract/Free Full Text]
- Shaw LJ, Raggi P, Schisterman E, Berman DS, Callister TQ.
Prognostic value of cardiac risk factors and coronary artery calcium screening
for all-cause mortality. Radiology 2003;228
: 826–833[Abstract/Free Full Text]
- McClelland RL, Chung H, Detrano R, Post W, Kronmal RA. Distribution
of coronary artery calcium by race, gender, and age: results from the
Multi-Ethnic Study of Atherosclerosis (MESA).
Circulation 2006;113
: 30–37[Abstract/Free Full Text]
- White CS. Chest pain in the emergency department: potential role of
multidetector CT. J Thorac Imaging 2007;22
: 49–55[CrossRef][Medline]
- Schoepf UJ, Zwerner PL, Savino G, Herzog C, Kerl JM, Costello P.
Coronary CT angiography. Radiology 2007;244
: 48–63[Abstract/Free Full Text]
- Thoongsuwan N, Stern EJ. Chest CT scanning for clinical suspected
thoracic aortic dissection: beware the alternate diagnosis. Emerg
Radiol 2002; 9:257
–261[Medline]
- Stein PD, Fowler SE, Goodman LR, et al. Multidetector computed
tomography for acute pulmonary embolism. N Engl J Med2006; 354:2317
–2327[Abstract/Free Full Text]
- Perrier A, Roy PM, Sanchez O, et al. Multidetector-row computed
tomography in suspected pulmonary embolism. N Engl J
Med 2005; 352:1760
–1768[Abstract/Free Full Text]
- Righini M, Le Gal G, Aujesky D, et al. Diagnosis of pulmonary
embolism by multidetector CT alone or combined with venous ultrasonography of
the leg: a randomised non-inferiority trial. Lancet2008; 371:1343
–1352[CrossRef][Medline]
- Nienaber CA, Eagle KA. Aortic dissection: new frontiers in
diagnosis and management. Part I. From etiology to diagnostic strategies.
Circulation 2003;108
: 628–635[Free Full Text]
- Erbel R, Alfonso F, Boileau C, et al. Diagnosis and management of
aortic dissection. Eur Heart J 2001;22
:1642
–1681[Free Full Text]
- Ehara M, Surmely JF, Kawai M, et al. Diagnostic accuracy of
64-slice computed tomography for detecting angiographically significant
coronary artery stenosis in an unselected consecutive patient population:
comparison with conventional invasive angiography. Circ
J 2006; 70:564
–571[CrossRef][Medline]
- Fine JJ, Hopkins CB, Ruff N, Newton FC. Comparison of accuracy of
64-slice cardiovascular computed tomography with coronary angiography in
patients with suspected coronary artery disease. Am J
Cardiol 2006; 97:173
–174[CrossRef][Medline]
- Leschka S, Alkadhi H, Plass A, et al. Accuracy of MSCT coronary
angiography with 64-slice technology: first experience. Eur Heart
J 2005; 26:1482
–1487[Abstract/Free Full Text]
- Mollet NR, Cademartiri F, van Mieghem CA, et al. High-resolution
spiral computed tomography coronary angiography in patients referred for
diagnostic conventional coronary angiography.
Circulation 2005;112
:2318
–2323[Abstract/Free Full Text]
- Oncel D, Oncel G, Tastan A, Tamci B. Detection of significant
coronary artery stenosis with 64-section MDCT angiography. Eur J
Radiol 2007; 62:394
–405[CrossRef][Medline]
- Ong TK, Chin SP, Liew CK, et al. Accuracy of 64-row multidetector
computed tomography in detecting coronary artery disease in 134 symptomatic
patients: influence of calcification. Am Heart J2006; 151:1323
- Raff GL, Gallagher MJ, O'Neill WW, Goldstein JA. Diagnostic
accuracy of noninvasive coronary angiography using 64-slice spiral computed
tomography. J Am Coll Cardiol 2005;46
: 552–557[Abstract/Free Full Text]
- Ropers D, Rixe J, Anders K, et al. Usefulness of multidetector row
spiral computed tomography with 64- x 0.6-mm collimation and 330-ms
rotation for the noninvasive detection of significant coronary artery
stenoses. Am J Cardiol 2006;97
: 343–348[CrossRef][Medline]
- Herzog C, Zwerner PL, Doll JR, et al. Significant coronary artery
stenosis: comparison on per-patient and per-vessel or per-segment basis at
64-section CT angiography. Radiology2007; 244:112
–120[Abstract/Free Full Text]
- Brodoefel H, Burgstahler C, Tsiflikas I, et al. Dual-source CT:
effect of heart rate, heart rate variability, and calcification on image
quality and diagnostic accuracy. Radiology2008; 247:346
–355[Abstract/Free Full Text]
- Johnson TR, Nikolaou K, Busch S, et al. Diagnostic accuracy of
dual-source computed tomography in the diagnosis of coronary artery disease.
Invest Radiol 2007;42
: 684–691[CrossRef][Medline]
- Leber AW, Johnson T, Becker A, et al. Diagnostic accuracy of
dual-source multi-slice CT-coronary angiography in patients with an
intermediate pretest likelihood for coronary artery disease. Eur
Heart J 2007; 28:2354
–2360[Abstract/Free Full Text]
- Ropers U, Ropers D, Pflederer T, et al. Influence of heart rate on
the diagnostic accuracy of dual-source computed tomography coronary
angiography. J Am Coll Cardiol 2007;50
:2393
–2398[Abstract/Free Full Text]
- Weustink AC, Meijboom WB, Mollet NR, et al. Reliable high-speed
coronary computed tomography in symptomatic patients. J Am Coll
Cardiol 2007; 50:786
–794[Abstract/Free Full Text]
- Sato Y, Matsumoto N, Ichikawa M, et al. Efficacy of multislice
computed tomography for the detection of acute coronary syndrome in the
emergency department. Circ J 2005;69
:1047
–1051[CrossRef][Medline]
- Hoffmann U, Nagurney JT, Moselewski F, et al. Coronary
multidetector computed tomography in the assessment of patients with acute
chest pain. Circulation 2006;114
:2251
–2260[Abstract/Free Full Text]
- Gallagher MJ, Ross MA, Raff GL, Goldstein JA, O'Neill WW, O'Neil B.
The diagnostic accuracy of 64-slice computed tomography coronary angiography
compared with stress nuclear imaging in emergency department low-risk chest
pain patients. Ann Emerg Med 2007;49
: 125–136[CrossRef][Medline]
- Goldstein JA, Gallagher MJ, O'Neill WW, Ross MA, O'Neil BJ, Raff
GL. A randomized controlled trial of multi-slice coronary computed tomography
for evaluation of acute chest pain. J Am Coll Cardiol2007; 49:863
–871[Abstract/Free Full Text]
- Rubinshtein R, Halon DA, Gaspar T, et al. Usefulness of 64-slice
cardiac computed tomographic angiography for diagnosing acute coronary
syndromes and predicting clinical outcome in emergency department patients
with chest pain of uncertain origin. Circulation2007; 115:1762
–1768[Abstract/Free Full Text]
- Hoffmann U, Pena AJ, Moselewski F, et al. MDCT in early triage of
patients with acute chest pain. AJR 2006;187
:1240
–1247[Abstract/Free Full Text]
- Rubinshtein R, Halon DA, Gaspar T, et al. Impact of 64-slice
cardiac computed tomographic angiography on clinical decision-making in
emergency department patients with chest pain of possible myocardial ischemic
origin. Am J Cardiol 2007;100
:1522
–1526[CrossRef][Medline]
- Schussler JM, Smith ER. Sixty-four-slice computed tomographic
coronary angiography: will the "triple rule out" change chest pain
evaluation in the ED? Am J Emerg Med2007; 25:367
–375[CrossRef][Medline]
- Boden WE, McKay RG. Optimal treatment of acute coronary syndromes:
an evolving strategy. N Engl J Med 2001;344
:1939
–1942[Free Full Text]
- Ladapo JA, Hoffmann U, Bamberg F, et al. Cost-effectiveness of
coronary MDCT in the triage of patients with acute chest pain.
AJR 2008; 191:455
–463[Abstract/Free Full Text]
- Otero HJ, Rybicki FJ. Reimbursement for chest-pain CT: estimates
based on current imaging strategies. Emerg Radiol2007; 13:237
–242[CrossRef][Medline]
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Abstract
Introduction
